Glass forming machine with individually controlled plunger end positions

Abstract

A glass forming machine and a method for manufacturing formed glass parisons. A glass forming machine includes a blank side for forming parisons from gobs of molten glass. The blank side includes a plunger and a blank mould. The plunger can be moved into the blank mould up to an end position. The plunger can be moved out of the blank mould up to a start position. The glass forming machine includes a glass feeding device which is configured to bring a gob of molten glass into the blank mould. The glass forming machine includes a measuring device which is configured to measure the end position of the plunger. The glass feeding device is configured such that the size of a gob of molten glass depends on the end position previously reached during operation. Parisons of good quality can be produced with a bigger tolerance of mould volumina.

1 . A glass forming machine which includes a blank side for forming parisons from gobs of molten glass; the blank side includes a plunger and a blank mould; the plunger can be moved into the blank mould up to an end position; the plunger can be moved out of the blank mould up to a start position; the glass forming machine includes a glass feeding device which is configured to bring a gob of molten glass into the blank mould; the glass forming machine includes a measuring device which is configured to measure the end position of the plunger, wherein the glass feeding device is configured such that the size of a gob of molten glass depends on the end position previously reached during operation. 
     
     
         2 . The glass forming machine according to  claim 1 , wherein the glass forming machine includes a memory for storing an end position range or a set point value, the glass feeding device is configured to change the size of a gob of molten glass if an end position of the plunger previously reached during operation is not within a stored end position range or if an end position didn't reach the set point value, the size of the gob of molten glass then being changed such that, as a result of the change, the subsequently reached end position is within the range or reaches the set point value. 
     
     
         3 . The glass forming machine according to  claim 1 , wherein the glass feeding device comprises:
 a feeder bowl adapted for containing molten glass, said feeder bowl having a discharge orifice,   a movable needle,   an electrical motor adapted to move the needle with respect to the discharge orifice,   a control device which is configured to control the movement of the needle,   a sensor for detecting an information associated with a position of the needle in order to control the movement of the needle, and   a shear mechanism which is configured to divide a stream of molten glass emerging from the discharge opening into gobs of molten glass.   
     
     
         4 . The glass forming machine according to  claim 3 , wherein the control device is configured to control the movement of the needle such that the size of a gob of molten glass depends on the end position previously reached during operation. 
     
     
         5 . The glass forming machine according to  claim 3 , wherein the control device is configured to increase and decrease the diameter of the stream in an oscillating and/or wave-like manner. 
     
     
         6 . The glass forming machine according to  claim 3 , wherein the electrical motor is different from a stepper motor. 
     
     
         7 . The glass forming machine according to  claim 6 , wherein the electrical motor is a brushless DC motor or a synchronous or an asynchronous electrical motor or a linear motor. 
     
     
         8 . The glass forming machine according to  claim 3 , wherein the sensor ( 65 ) is configured to detect a rotor position of the electrical motor. 
     
     
         9 . The glass forming machine according to  claim 3 , wherein the sensor ( 65 ) is a resolver or an encoder like an incremental encoder. 
     
     
         10 . The glass forming machine according to  claim 1 , wherein the blank side includes at least one section for simultaneously forming a plurality of parisons from gobs of molten glass, the section comprising at least two plungers and a at least two blank moulds; each plunger of a section being associated with one blank mould of the section; each plunger can be moved into the respective blank mould up to an end position; each plunger can be moved out of the respective blank mould up to a start position; the glass forming machine including for each section at least two needles and two discharge orifices, each discharge orifices being associated with one of the blank moulds of the section and configured to bring a gob of molten glass into the respective blank mould; the glass forming machine including a plurality of measuring devices, each measuring device being associated with one of the plungers of the section and configured to measure the end position of the respective plunger, wherein the glass feeding device is configured such that the size of a gob of molten glass brought into one of the blank moulds of a section depends on the end position of the plunger associated with said blank mould previously reached during operation,
 wherein, in particular, the glass forming machine comprises at least two sections.   
     
     
         11 . The glass forming machine according to  claim 10 , wherein each glass feeding device comprises a discharge orifice, a movable needle, an electrical motor adapted to move the needle with respect to the discharge orifice, a control device which is configured to control the movement of the needle, and a sensor for detecting a position of the needle in order to control the movement of the needle,
 wherein, in particular, the control device is configured to control the movement of the needle such that the size of a gob of molten glass brought into one of the blank moulds of a section depends on the end position of the plunger associated with said blank mould previously reached during operation.   
     
     
         12 . A method for manufacturing formed glass parisons, in particular with a glass forming machine according to one of the previous claims, comprising
 Forming a first parison from a first gob of molten glass by means of a blank side having a plunger and a blank mould, including bringing the first gob of molten glass into the blank mould by means of a glass feeding device and moving the plunger up to the end position,   Measuring the end position of the plunger by means of a measuring device,   Forming a second parison from a second gob of molten glass by means of the blank side, including bringing the second gob of molten glass into the blank mould by means of the glass feeding device and moving the plunger up to the end position, such that the size of the second gob of molten glass depends on the measured end position.   
     
     
         13 . The method according to  claim 12 , wherein a needle of the glass feeding device is moved with respect to the discharge orifice by an electrical motor previously to and/or during bringing the second gob of molten glass into the blank mould such that the size of the second gob of molten glass depends on the measured end position. 
     
     
         14 . The method according to  claim 13 , wherein the movement of the needle is controlled by means of a control device based on an information associated with a position of the needle detected by a sensor. 
     
     
         15 . The method according to  claim 12 , wherein in a plurality of blank sides a plurality of first parisons are formed from a plurality of first gobs of molten glass and subsequently, in said plurality of blank sides, a plurality of second parisons are formed from a plurality of second gobs of molten glass such that the size of each of the second gobs of molten glass depends on the previously measured end position of the plunger of the respective blank side during formation of the first gobs of molten glass.